MicroSquirt.com read only forum (Jan.15,2018)

I'm running a msII v.3. My fuel pump doesn't turn on. the LED on the ms lights up, but the one on the stim doesn't. how do I trouble shoot the circuit?

feldz82,

There are only 5 components on the fuel pump circuit for the V3 boards:

- R16 (the 1K Ohm base resistor for Q2),
- Q19 (the 2N3904 transistor),
- Q2 (the ZTX450 transistor),
- R40 (the 1 Ohm, 1/2W resistor),
- D4 (22V Zener 'flyback' diode).

Any of these could cause a problem, so check them all, but most commonly the problem is a solder bridge between the very closely spaced leads of the transistors. Use a solder wick (a fine braid of woven copper) to remove any excess solder. Also check that D4 is in the right way around, and that the resitors are well soldereed but not bridge to any adjacent components.

Lance.

thanks for the response, I'll check them out